array_fill 填充数组内容

<?php
$a = array_fill(, , 'banana');
$b = array_fill(-, , 'pear');
print_r($a);
print_r($b)

Array
(
    [5]  => banana
    [6]  => banana
    [7]  => banana
    [8]  => banana
    [9]  => banana
    [10] => banana
)
Array
(
    [-2] => pear
    [0] => pear
    [1] => pear
    [2] => pear
)